Virtualization may be viewed as abstraction of hardware components into logical objects in order to allow a computer system to execute various software modules, for example, multiple operating systems, concurrently and in isolation from other software modules. Virtualization may be achieved by running a software layer, often referred to as a “virtual machine monitor,” above the hardware and below the virtual machines. The virtual machine monitor may abstract the physical layer and present this abstraction to virtual machines to use, by providing interfaces between the underlying hardware and virtual devices of virtual machines. For example, processor virtualization may be implemented by the virtual machine manager scheduling time slots on one or more physical processors for a virtual machine, rather than a virtual machine actually having a dedicated physical processor.